Sphere grinding and polishing apparatus

ABSTRACT

GRINDING, LAPPING, AND SMOOTHING APPARATUS TO PRODUCE A PRECISION SPHERICAL OBJECT. THE APPARATUS GENERALLY COMPRISES A WORK PIECE HOLDING AND GRIT APPLYING STATION AND A PAIR OF GRINDING STATIONS MOUNTED ON A SUPPORTING FRAME. THE WORK PIECE STATION IS CENTRALLY DISPOSED WITHIN THE SUPPORTING FRAME AND INCLUDES A ROTATABLE, SPRING RELIEVED, GRIT APPLICATION PAN WHICH CAN BE ELEVATED WITH RESPECT TO THE FRAME. EACH GRINDING STATION HAS A SPRING RELIEVED GRINDING HEAD ASSEMBLY WHICH IS LATERALLY, LONGITUDINALLY, AND TILTABLY MOVABLE WITH RESPECT TO THE WORK PIECE STATION.

1971 H. F. HILLMAN SPHERE GRINDING AND POLISHING APPARATUS I5 Sheets-Sheet 1 Filed March 9, 1970 INVENTOR.

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1971 H. F. HILLMAN SPHERE GRINDING AND POLISHING APPARATUS I5 Sheets-Sheet '2 Filed March 9, 1970 INVENTOR. Ham/d fI fiW/mazr orrm/vzxs I'll Oct. 5, 1971 H|LLMAN 3,609,918

SPHERE GRINDING AND POLISHING APPARATUS Filed March 9, 1970 3 Sheets-Sheet 3 t //2 //3/07 a2, 46: 1Z2

INVENTOR.

Harm/d fT hW/man IQTTORIVEY United States Patent US. Cl. 51117 6 Claims ABSTRACT OF THE DISCLOSURE Grinding, lapping, and smoothing apparatus to produce a precision spherical object. The apparatus generally comprises a work piece holding and grit applying station and a pair of grinding stations mounted on a supporting frame. The work piece station is centrally disposed within the supporting frame and includes a rotatable, spring relieved, grit application pan which can be elevated with respect to the frame. Each grinding station has a spring relieved grinding head assembly which is laterally, longitudinally, and tiltably movable with respect to the work piece station.

BACKGROUND AND SUMMARY OF THE INVENTION -In various fields of art, there is frequently a need for a truly precise spherical object which may be fabricated from any number of materials including stone, metal or synthetics. The wide diversity of this need is evidenced in bowling balls, rotors in navigational gyroscopes, large ball bearings, and art objects, to mention a few examples.

This invention relates to apparatus for precisely grinding, lapping and polishing the surface of a spherical object and, more particularly, to apparatus for producing a precision spherical stone ball. A typical device of this nature includes a plurality of rotatable grinding cones which engage the work piece to impart in random fashion the grinding, lapping and polishing necessary to produce a precision sphere. It is known that an abrasive or grit applied to the work piece greatly facilitates this operation.

Of the devices of which I am presently aware, all require the continuous presence of an operator to apply grit to the Work piece and to make periodic adjustments of the grinding cones either toward or away from the work piece. There remains a need in the art for an apparatus to precisely grind, lap and polish the surface of a spherical ball without requiring the continuous supervision of an operator. Likewise, there is a need for an apparatus which will automatically and randomly apply grit to the work piece during the grinding operation.

The primary object of this invention is to provide a grinding lapping and polishing apparatus particularly adapted for work on stone balls to create a precision sphere without constant supervision of an operator.

Another object of the invention is to provide a grinding, lapping and polishing apparatus in which abrasive material is continuously and randomly applied to the work piece.

An additional object of the invention is to provide a grinding, lapping and polishing apparatus of the character described having great versatility with respect to positioning and adjusting the grinding members.

A further object of the invention is to provide an apparatus of the character described in which pressure from the grinding members is greatest during the initial grinding operation and gradually decreases during the final polishing operation without play between the work piece and the grinding members. This feature utilizes the characteristic inherent in the grinding operation that the work piece gradually wears away and the characteristic unique to this apparatus that all members engaging the work 3,609,918 Patented Oct. 5, 1971 piece are spring loaded to permit an even distribution of the compressive forces applied to the work piece during the entire grinding and polishing operation.

Other and further objects of the invention, together with features of novelty appurtenant thereto, will appeal in the course of the following description of the drawings.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith, and in which like reference numerals are employed to indicate like parts in the various views:

FIG. 1 is a front elevational view of the grinding apparatus constructed in accordance with a preferred embodiment of the invention with central portions of the supporting frame cut away to show additional details of construction and with the grinding cone of one grinding station removed;

FIG. 2 is a side view along line 22 of FIG. 1 in the direction of the arrows;

FIG. 3 is an enlarged plan view of the work piece station along line 3-3 of FIG. 2 in the direction of the arrows;

FIG. 4 is a rear view of the apparatus along line 44 of FIG. 2 in the direction of the arrows;

FIG. 5 is an enlarged sectional view along line 55 of FIG. 4 in the direction of the arrows;

FIG. 6 is a sectional view along line 66 of FIG. 5 in the direction of the arrows;

FIG. 7 is an enlarged sectional view along line 77 of FIG. 6 in the direction of the arrows;

FIG. 8 is a plan View of the supporting construction of one grinding station;

FIG. 9 is an end view along line 9-9 of FIG. 8 in the direction of the arrows;

FIG. 10 is an end view along line 10-10 of FIG. 8 in the direction of the arrows;

FIG. 11 is a side view along line 11-11 of FIG. 8 in the direction of the arrows; and

FIG. 12 is an underside view along the line 12-12 of FIG. 11 in the direction of the arrows.

Referring to the drawings in more detail, the grinding apparatus as viewed in FIGS. 1 and 4, can be generally subdivided into a work piece station 20, a pair of grinding stations 21 and 21, and a table-like supporting frame 22.

The supporting frame The frame 22 is constructed from a plurality of upright legs 23 which are interconnected by end bracing 24, upper side members 25, and lower side members 26. Secured by lags 27 to the exterior surface of the upper side members 25 are a plurality of upright struts 28 which project above the upper surface of the side members 25. As best viewed in FIG. 5, angle rails 29 are securely afiixed to the upper end of the struts 28 which a portion thereof projecting inwardly.

Centrally disposed within the supporting frame 22 is an open, inner frame, the members of which are designated by numeral 30, suitably connected to the upper side members 25 and the lower side members 26.

The work piece station The general function of the work piece station 20', as viewed in FIGS. 1 through 6, is to retain the work piece and to apply grit thereto during the grinding operation. With particular reference to FIG. 5, a grit application pan 3-1 is received within an open topped housing 32. Also within the housing 32 is a spring mount 33 to which the application pan 31 is connected by a nut and bolt 34 to the upper plate 33a thereof. The upper plate 33a is remotely interconnected to a lower plate 3% by a plurality of helical springs 33c attached therebetween. The lower plate 33b is connected by a nut 35 to the threaded end of a rotatable shaft '36 which extends downwardly through the housing 32. A spacer bearing 37 associated with the shaft 36 is interposed between the surface of the plate 33b and the interior bottom of the housing 32. A mud shield 38 within the housing 32 encircles the lower plate 33b to prevent material within the housing 32 from contacting the spacer bearing 37.

Attached to the under surface of the housing '32 is a multi-sided partition member 39 of which two side walls thereof have associated bearing mounts 40* and 41 which receive the rotatable shaft 36. Also connected to the partition member 39 are downwardly projecting runners 42 and 43 which are interconnected at the lower end thereof by bolts 44 to a horizontal brace 45.

Secured to the inner frame members 30 and adjacent each runner 42 and 43, are vertical guide tracks 46 and 47, respectively, which are interconnected by bolts 48 at the lower ends thereof to a cross member 49. As viewed in FIG. 7, the guide track 46 is formed from an outer member 46a, intermediate spacer members 4612, and offset members 46c to provide a T-shaped channel 50 which slidably receives the runner 42.

Associated with the cross member 49 is a bearing mount 51 which receives a vertical threaded shaft 52 which, in turn, extends upwardly and threadably engages a nut member 53 rigidly aflixed to the horizontal brace 45. The lower end of the shaft 52 terminates in a bevel gear 54. The bevel gear '54 is engaged by a bevel gear 55 mounted on a horizontal shaft 56 which is supportingly received by inner frame members 30 and terminates in a hand crank 57 at one end thereof, as best viewed in FIG. 6.

Mounted on the inner frame members 30 and between the lower side members 26, is a motor 58 having an output shaft 59 connected by a shaft coupling 60 to the input shaft 61 of a gear reduction box 62. The output shaft 63 from the gear reduction box 62 extends upwardly in axial alignment with the rotatable shaft 36 associated with the grit application pan 31 as previously described. An elongate sleeve member 64 receives the output shaft 63 and the rotatable shaft 36 as viewed in FIG. 5. At each end of the sleeve '64 are set bolts 65 and 66, one of which (bolt 65) engages the output shaft 63 and the other of which (bolt 66) engages the rotatable shaft 36.

S constructed, rotation of the output shaft 63, provided by the motor 58, is transmitted via the sleeve 64 to drive the rotatable shaft 36. The grit application pan 31 and the spring mount 33 are thereby rotated in response to rotation of the shaft 36.

When the set bolts 65 and 66 associated with the sleeve 64 are loosened, the hand crank 57 can be turned to impart rotation to the threaded shaft 52 through the bevel gears 55 and 54. Rotation of the threaded shaft 52 acts upon the nut member 53 attached to the horizontal brace 45 to move the runners 42 and 43 upwardly or downwardly in the guide tracks 46 and 47, respectively, and thereby raise or lower the housing 32 having associated therewith the grit application pan 31. Once the housing 32 is adjusted to a new position, the set bolts 65 and 66 can be retightened to again engage the output shaft 63 and rotatable shaft 36, respectively, after which the pan 31 again can be rotatably driven by the motor 58.

Attached to the upper side members 25 and centrally adjacent the grit application pan 31, are tubular sleeves 67 and 68 having thumb screws 69 and 70, respectively, as viewed in FIG. 5. The sleeve 67 receives an extension 71 which has a horizontal tubular sleeve 72 with an associated thumb screw 73 attached to the upper end thereof. The sleeve 72 receives an extension 74 having one end thereof pivotally connected by a pin member 75 to an abrasive guide 76 which extends into the grit application pan 31.

At the rear of the frame 22, the tubular sleeve 68 receives an extension 77 having a horizontal tubular sleeve 78 with ah associated thumb screw 79 attached to the upper end thereof. The horizontal sleeve 78 receives an extension 80 having a splash guard 81 attached to the inner end thereof which extends into the grit application pan 31.

So constructed, the abrasive guide 76 can be raised or lowered with respect to the pan 31 by loosening the thumb screws 69 and raising or lowering the extension 71 within the sleeve 67. Likewise, the abrasive guide 76 can be adjusted with respect to the center of the pan 31 by loosening the thumb screw 73 and slidably moving the extension 74 within the sleeve 72.

The splash guard 81 can be raised or lowered with respect to the pan 31 by loosening the thumb screws 70 and raising or lowering the extension 77 within the sleeve 68. Likewise, the splash guard 81 can be adjusted with respect to the center of the pan 31 by loosening the thumb screw 79 and slidably moving the extension 80 within the sleeve 78.

The grinding stations Disposed on opposite sides of the work piece station 20 are grinding stations 21 and 21 now to be described in detail. Since the grinding stations are identicai in con struction, one will be described employing unprimed reference numerals and like parts of the other grinding station will be indicated by primed reference numerals.

As viewed in FIGS. 1 and 4, the grinding station 21 includes a motor 82 having an output hub 83 on which is mounted a spring loaded plate assembly 84 of similar construction to the spring mount 33 previously described with reference to FIG. 5. Connected to the outer end of the assembly 84 is a shaft 85 which receives a cup member 86 on which is mounted a grinding cone 87. The remaining portion of the grinding station 21 comprises the supporting structure which connects the motor 82 to the frame 22.

As viewed generally in FIGS. 8 through 12, the grinding station 21 includes an underlying support frame having end members 88 and 89 rigidly attached at the ends thereof to side members 90 to provide an open, square frame construction. Attached to side members 90 are C-shaped channel members 91 which, as viewed in FIG. 2, have associated therewith thumb screws 92 operable to engage the angle rails 29 of the supporting frame 22. Loosening the thumb screws 92 permits the channel members 91 to slide along the angle rails 29 whereby the underlying support frame can be removed from the supporting frame 22 or longitudinally adjusted with respect to the work piece station 20.

Disposed between the channel members 91 are a pair of longitudinal bars 93 which rest on the end members 88 and 89. The bars 93 are rigidly affixed to cross members 94 and 95 which overlyingly engage the end members 88 and 89, respectively. To the innermost cross member 94 is connected, by bolts 96, spacer bars 97 and a strap member 98 which slidably engages the underside of the end member 88, as viewed in FIGS. 11 and 12.

Attached by bolts 99 to the outermost cross member '95 are spacers 100 and a tongue 101 which extends beneath the end member 89. Constructed in this fashion, the strap 98 and tongue 101 connect the longitudinal bars 93 to the end members 88 and 89 to permit slidable, lateral movement thereon.

A pair of upright ears 102 are attached by bolt means 103 to the innermost end of the longitudinal bars 93 and extend upwardly therefrom to pivotally receive on bolts 104 the innermost end of a .tiltable, grinder table 105 which includes longitudinal members 106 operable to overlyingly engage the previously mentioned longitudinal bars 93 and a plate member 107 attached to the upper edges of the longitudinal members 106.

Near the outermost end of the longitudinal members 106 is interconnected a pivotal shaft 108 which receives the end of a threaded shaft 109 to permit rotation of the shaft 109 therein. Likewise, near the outermost end of the longitudinal bars 93, there is interconnected a pivotal shaft 110 having a threaded axial bore therein (not shown) to receive in threadable engagement the threaded shaft 109. The shaft 109 extends downwardly and terminates in a hand crank 111 (FIG. 9). By manual rotation of the crank 111, the grinder table 105 can be adjustably tilted about the innermost end thereof by extending or retracting the threaded shaft 109 within the bore of the pivotal shaft 110.

Attached to the ends of the plate member 107 are upstanding plates 112 between which are mounted, above the plate 107, the guide rods 113 which slidably receive ring members 114 projecting downwardly from the underneath side of a grinder platform 115. As viewed in FIG. 8 the grinder platform 115 includes a plurality of holes 116 therein to provide means for connecting the grinder motor 82 (shown in broken lines).

Also attached to the underneath side of the grinder platform 115 is a nut member (not shown) which threadably receives an elongate threaded shaft 117 which, in turn, is rotatably supported by the upstanding plate 112 at each end of the grinder table 105. The outer end of the shaft 117 terminates in a hand crank 118. By manual rotation of the hand crank 118, the grinder platform 115 can be adjustably moved throughout the length of the grinder table 105.

In operation, the sphere grinding and polishing apparatus is normally employed to produce a precisionally spherical stone ball in the manner to be described.

The stone to be ground into a spherical shape is first cubed by sawing. All eight corners of the cubed stone are then cut off and the deges are rounded. At this point, the Work piece can be received by the grinding apparatus constructed in accordane with the principles of this invention.

The work piece 119 is placed in the grit application pan 31, as viewed in FIG. 3. Depending upon the size of the work piece, various initial adjustments of the work piece station 20 and grinding stations 21 and 21' may be made as previously described. Such adjustments can include raising and lowering the application pan 31 with the hand crank 57, moving the grinding cones 87 toward or away from the work piece by sliding the assembly on the angle rails 29, laterally moving the grinding cones 87 with respect to the work piece by sliding the assembly on end members 88 and 89, changing the angle at which the grinding cones 87 bear upon the work piece via the hand crank 111, and changing the force at which the grinding cones 87 bear against the work piece with the hand crank 118. Likewise, appropriate adjustments to the abrasive guide 76 and the splash guard 81 may be made.

When such adjustments have been made, and a suitable grit or "abrasive is placed in tthe pan 31, the grinding cones 87, driven by motors 82, rotate against the work piece to impart random grinding action thereto. During the initial grinding operation, the springs of mount 33 and assembles 84 may be slightly compressed to achieve a two-fold function of compensating for the irregular surface of the work piece and of urging the grinding cones 87 to engage the work piece as portions thereof are worn away during grinding. The grit application pan 31 rotates toward the front face of the abrasive guide 76 as viewed in FIG. 3. The guide 76 causes the abrasive to move inwardly toward the work piece which picks up the abrasive as it randomly spins and rotates between the application pan 31 and the grinding cones 87.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. As many possible embodiments may be made of the nvention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A grinding and polishing apparatus to produce spherical objects, said apparatus comprising:

a supporting frame;

a work piece station centrally disposed within said sup porting frame and having a rotatable, resiliently biased grit application pan; and

a pair of grinding stations mounted on said supporting frame adjacent opposite sides of said work piece station, each said grinding station including a rotatable, resiliently biased grinding head.

2. The apparatus as in claim 1, said work piece station including a stationary frame connected to said supporting frame and a movable frame associated with said grit application pan and adjustably received by said stationary frame to permit said grit application pan and said movable frame to be raised or lowered with respect to said stationary frame.

3. The apparatus as in claim 1, each of said grinding stations being reciprocably carried by said supporting frame to permit longitudinal movement of said stations toward or away from said work piece station.

4. The apparatus as in claim 1, each of said grinding stations including an underlying support frame to permit lateral adjustment of said grinding heads with respect to said work piece station.

5. The apparatus as in claim 1, each of said grinding stations including a tiltable platform associated with said grinding heads to permit angular adjustment of said heads with respect to said work piece station.

6. The apparatus as in claim 1, said work piece station including an abrasive guide adjustably mounted to said supporting frame and projecting inwardly to said grit application pan.

References Cited UNITED STATES PATENTS 3,110,987 11/1963 Arneson 51-117 2,787,093 4/1957 Sundberg 511 17 X 3,167,884 2/1965 Thompson 51-117 X HAROLD D. WHITEHEAD, Primary Examiner 

